Influence of dehydration and rehydration on photosynthetic chlorophyll characteristics and reactive oxygen species metabolism in Dolichomitriopsis diversiformis Photochemical analysis of PSII in response to dehydration and rehydration in moss Grimmia pilifer P.Beauv Reactive Oxygen Species Metabolism and Membrane Lipid Peroxidation of Polytrichum commune and Plagiomnium acutum during Fast Drying and Rehydration